This jellyfish often occurs in swarms, either in the Bay or washed up on the beaches. Here and in southern Queensland they are commonly blue. They may be brown or white in other areas. The brown colour is caused by symbiotic algae. They are often accompanied by small fish. The sting is not generally considered to be serious.

This species can be distinguished by its conspicuous internal cross. They have very fleshy, three-winged arms around their mouths. A full complement is eight, but they are often seen fewer arms or with pieces missing. There is no obvious mouth on the underside, but there are small openings on each arm, through which food is passed to the stomach